In a large-sized vehicle, such as a bus, due to an increased heat dissipation rate from exhaust gas regulation strengthening and power enhancement, as shown FIGS. 1 and 2, a radiator for cooling an engine is installed at a lateral side of a vehicle along a longitudinal orientation.
The vehicle includes a cooling fan 13 for drawing in ambient air and transferring it into the radiator 12. The cooling fan 13 is activated by a fan clutch, and a driving power generated from the engine 11 is transferred through a crank pulley 14 to a gear box 15 of the fan clutch.
However, according to the conventional technology described above, a negative pressure is generated around the cooling fan 13 due to the operation of the cooling fan 13 and hot air flows into the region where the gear box 15 is installed. Therefore, this raises the temperature in the region on which the fan clutch is installed.
When the cooling fan is operated, a greater amount of cool air coming from the outside is radiated toward the circumference of the cooling fan 13. However, because of a negative pressure of a central portion at the time of rotation of the cooling fan 13, a portion of hot air flows into the gear box 15 of the fan clutch from hot parts such as an engine, EGR system or a turbocharger.
In this way, at the time of the operation of the cooling fan 13, hot air around the engine 11 flows toward the gearbox 15 of the fan clutch and consequently the temperature of the inside of the gearbox 15 of the fan clutch is increased. As a result, an oil seal within the gearbox of the fan clutch may become damaged and the oil may become degraded.